2005-08-15

The main reason for venturing out was to give the 130M a proper "run
under the stars" after
center
spotting the primary mirror on 2005-08-13. Also, before heading
out, I use a laser collimator to try and improve the collimation. I
didn't plan on doing any star-tests tonight — I just wanted to
see how well I got on with the 'scope having actually had the mirror
out of it.

Moon was a waxing gibbous quite low in the sky (not visible from my
position). There was some thin haze in parts of the sky but no
noticeable clouds. Temperature was cool but still warm enough to be
out in a t-shirt.

General testing

Started out by pointing the 'scope at Mizar. With the
25mm eyepiece there was some obvious "flaring" of the brighter
stars in the field. I could also see, from time to time, a faint
"rainbow" effect in the flare. At this point I had trouble
recalling exactly how bright stars used to look in the 'scope.
I've always seen some flaring but — never having really made
a point of noting exactly how it appeared —
I didn't really have anything to compare. Lesson for the future:
make notes about the really obvious things such as how stars look
before you do some work on your 'scope.

With the 15mm eyepiece the flare (which, at times, looked like a
very tight double image of each bright star) had a noticeable
difference in appearance either side of best focus. When unfocused
either side there was the impression of an oval effect to the
unfocused stars. Either side of focus the orientation of the oval
would rotate 90Â°. As I understand it this is evidence of
astigmatism in the primary or secondary mirror! I don't think I've
ever noticed this before (not that I've ever really gone looking
for it before).

I tried a few things to see if the oval effect would differ: I
changed eyes (no difference), changed my orientation at the
eyepiece (no difference) and rotated the eyepiece in the focuser
(no difference).

I then tested with the 10mm and then 6mm eyepieces and, as best as
I could tell, the oval effect wasn't noticeable. Most confusing.

The more I thought about it the more I felt that what I was seeing
actually wasn't any worse than the 'scope used to be. Also,
there's the fact that I don't generally know what a bright star
should look like through a smallish Newtonian Reflector.

I wished that I'd had Jupiter or Saturn around still so that I
could compare how things looked with a more "substantial" target.

Meteor

Probable Iridium Flare

Saw a very bright Iridium Flare in Ursa Major — just
below the "handle" of "The Plough". I got the impression that it
was one of the brightest flares I've ever seen. It was a
lot brighter than any of the stars in
Ursa Major.

M13

After the slight annoyance and frustration early on in the session
I decided to try the 'scope out on a DSO and opted for an easy
target: M13. Initial impression with the 25mm
eyepiece was that it looked magnificent! While it looked like a
cometary-like "blob" (as I'd noted in a
previous observing session) there was,
this time, the occasional faint hint that it was comprised of lots
of stars. It wasn't so much that I could see stars, it was more a
case of it looking slightly "grainy" from time to time.

Satellite between Cygnus and Lyra

Watched a faint satellite go roughly North to South, more or less
via the zenith, and pass between Cygnus and
Lyra. It seemed to occult a faint (to the naked eye)
star somewhere between the two constellations. Unfortunately, at
the time, I wasn't in a position to note which one it was.

M13

Went back to M13, this time with the 15mm eyepiece. Appeared
slightly brighter. There was now a hint that it's made of actual
stars with the grainy appearance mentioned above being much more
pronounced. While doing viewing a thin but obscuring line of cloud
(might even have been a contrail) moved into the
area and made observing rather hard. Somewhat annoying as I was
about to start a sketch of what it looked like with the 15mm
eyepiece.

M31 (and possibly M32)

M31 is now in a position where I can see it
with the 'scope. First looked at it with the 25mm eyepiece. M31
itself was obvious but, at the same time, indistinct. There was an
obvious brightness difference between what I assume is the central
bulge and between the disk. There was no hint of any sort of
structure and the whole thing had the appearance of a sort of
light-gray "mist". The fact that I was looking in the direction of
a street-light and that there was still a very faint haze in the
sky probably wasn't helping matters.

After a short while I noticed that a star in the field was
actually rather "fuzzy" when compared to all the other stars.
Started to wonder if what I was seeing was M32.
My initial impression was that it was further away from M31 than
I'd imagined it would appear to be but, that said, that impression
is formed from the photographs I've seen of M31 (which obviously
show a lot more of the galaxy than I'd be seeing through my
'scope).

Checking with a chart I had to hand the fuzzy object did appear to
be in about the right location for M32. To be sure I went and
checked with my copy of Sky Atlas 2000 and, looking at
that, I convinced myself that I wasn't seeing M32 (based on the
pattern of stars near it which seemed to be in SA2000 but not in
the correct position for M32). Lesson here: be sure of the width
of the field of view of the eyepiece so you can make good
estimates of separation of objects.

Switched to the 15mm eyepiece. The "fuzzy star" still had a fuzzy
appearance and still looked quite different from all other stars
in the field.

Mars pops up

As I was starting to pack up I noticed that Mars
had popped up over the roofs of the houses to the East of me. I
did consider setting up the 'scope again to have a look at it but
given that it was still low down and given that it was very close
to a street-light I decided to save that for another night when
conditions were a little more favourable.